Mobile Communication System

1. A mobile terminal device comprising: a request unit configured to send at least a request message for establishing only one Packet Data Network (PDN) connection which provides connectivity to a PDN associated with an access point name (APN), the PDN connection being used only for a communication between an external gateway device and a plurality of information terminal devices which include said at least one information terminal device; a reception unit configured to receive the APN, an evolved packet system (EPS) bearer ID, and an address block, the address block being allocated by the external gateway device to the PDN connection, and the EPS bearer ID being allocated to the PDN connection; and an allocation unit configured to allocate an IPv6 prefix based on the address block to the at least one information terminal device, and transfer, based on the EPS bearer ID, user data as a router from the at least one information terminal device to the PDN associated with the APN via the PDN connection, wherein the user data being transferred from the information terminal devices using an IP address configured based on the assigned IPv6 prefix.

2. The mobile terminal device according to claim 1 , wherein the address block is an IPv6 prefix shorter than an upper-order 64 bits.

3. An external gateway device comprising: an establishment unit configured to establish only one Packet Data Network (PDN) connection by a request, from a mobile terminal device, for establishing the PDN connection which provides connectivity to a PDN associated with an access point name (APN), the PDN connection being used only for a communication between the external gateway device and a plurality of information terminal devices which include said at least one information terminal device and the mobile terminal device being connected to the at least one information terminal device; an allocation unit configured to allocate an address block to the PDN connection, and notify the mobile terminal device of the address block; the establishment unit configured to establish a connection with the at least one information terminal device via the PDN connection; and a reception unit configured to receive user data transferred by the mobile terminal device from the at least one information terminal device via the PDN connection based on an evolved packet system (EPS) bearer ID transmitted to the mobile terminal device, and the EPS bearer ID being allocated to the PDN connection, wherein the user data being transferred from the information terminal devices using an IP address configured based on the assigned IPv6 prefix.

4. An external gateway device according to claim 3 , wherein the address block is an IPv6 prefix shorter than an upper-order 64 bits.

5. A mobile communication system comprising: at least one information terminal device; a mobile terminal device connected to the at least one information terminal device; and an external gateway device, wherein the mobile terminal device is configured to send at least a request message for establishing only one Packet Data Network (PDN) connection which provides connectivity to a PDN associated with an access point name (APN), the PDN connection being used only for a communication between the external gateway device and a plurality of information terminal devices which include said at least one information terminal device, the external gateway device is configured to allocate an address block to the PDN connection established by the request, and send the address block to the mobile terminal device, and the mobile terminal device is configured to: receive the APN, an evolved packet system (EPS) bearer ID, and the address block, and the EPS bearer ID being allocated to the PDN connection, allocate an IPv6 prefix based on the address block to the information terminal device, and transfer, based on the EPS bearer ID, user data as a router from the at least one information terminal device to the PDN associated with the APN via the PDN connection, wherein the user data being transferred from the information terminal devices using an IP address configured based on the assigned IPv6 prefix.

6. A method comprising: sending at least a request message for establishing only one Packet Data Network (PDN) connection which provides connectivity to a PDN associated with an access point name (APN), the PDN connection being used only for a communication between an external gateway device and a plurality of information terminal devices which include at least one information terminal device; receiving the APN, an evolved packet system (EPS) bearer ID, and an address block, the address block being allocated by the external gateway device to the PDN connection, and the EPS bearer ID being allocated to the PDN connection; and allocating an IPv6 prefix based on the address block to the at least one information terminal device, and transferring, based on the EPS bearer ID, user data as a router from the at least one information terminal device to the PDN associated with the APN via the PDN connection, wherein the user data being transferred from the information terminal devices using an IP address configured based on the assigned IPv6 prefix.

7. The method according to claim 6 , wherein the address block is an IPv6 prefix shorter than an upper-order 64 bits.

8. A method comprising: establishing only one Packet Data Network (PDN) connection by a request, from a mobile terminal device, for establishing the PDN connection which provides connectivity to a PDN associated with an access point name (APN), the PDN connection being used only for a communication between an external gateway device and a plurality of information terminal devices which include at least one information terminal device and the mobile terminal device being connected to the at least one information terminal device; allocating an address block to the PDN connection, and notify the mobile terminal device of the address block; establishing a connection with the at least one information terminal device via the PDN connection; and receiving user data transferred by the mobile terminal device from the at least one information terminal device via the PDN connection based on an evolved packet system (EPS) bearer ID transmitted to the mobile terminal device, and the EPS bearer ID being allocated to the PDN connection, wherein the user data being transferred from the information terminal devices using an IP address configured based on the assigned IPv6 prefix.

9. The method according to claim 8 , wherein the address block is an IPv6 prefix shorter than an upper-order 64 bits.

10. A method comprising: sending at least a request message for establishing only one Packet Data Network (PDN) connection which provides connectivity to a PDN associated with an access point name (APN), the PDN connection being used only for a communication between an external gateway device and a plurality of information terminal devices which include at least one information terminal device; allocating an address block to the PDN connection established by the request, and send the address block to a mobile terminal device; receiving the APN, an evolved packet system (EPS) bearer ID, and the address block, and the EPS bearer ID being allocated to the PDN connection; allocating an IPv6 prefix based on the address block to the information terminal device; and transferring, based on the EPS bearer ID, user data as a router from the at least one information terminal device to the PDN associated with the APN via the PDN connection, wherein the user data being transferred from the information terminal devices using an IP address configured based on the assigned IPv6 prefix.